The present invention relates to porous cross-linked polyvinyl alcohol particles that are produced by first dispersing in an organic solvent an aqueous solution of polyvinyl alcohol to make spheres of polyvinyl alcohol solution, holding the dispersion in such a state that a gel will form spontaneously, and then reacting the gel with a cross-linking agent. The present invention also relates to a process for producing such porous cross-linked polyvinyl alcohol particles, as well as a separating agent composed of such particles. More particularly, the present invention relates to porous cross-linked polyvinyl alcohol particles that are suitable for use as packing materials in chromatography, especially in aqueous-phase gel permeation chromatography.
Water-insoluble crosslinked polyvinyl alcohol particles that are produced by reacting polyvinyl alcohol with a cross-linking agent are known but the so obtained polyvinyl alcohol is in a gel state. A method has therefore been proposed for producing a porous cross-linked polyvinyl alcohol by reacting polyvinyl alcohol with a cross-linking agent in water in which a salt is dissolved or finely suspended (Unexamined Published Japanese patent application No. 90804/81).